Global warming roars on: Past four years have been Earth's hottest on record

NASA has released new maps that detail the effects of climate change around the world. As several areas in the U.S. are facing a blizzard, much of the western world is abnormally hot.
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This map shows Earth’s average global temperature from 2013 to 2017, as compared to a baseline average from 1951 to 1980, according to an analysis by NASA’s Goddard Institute for Space Studies. Yellows, oranges, and reds show regions warmer than the baseline.(Photo: NASA)

The string of the four warmest years on record across the globe continued in 2017, federal scientists announced Thursday.

NASA measured last year as the second-warmest on record, while the National Oceanic and Atmospheric Administration placed it in the third-warmest slot.

Both agencies reported 2017 was the warmest year without the effects of the El Niño climate pattern. The hottest year on record remains 2016, partly due to a strong El Niño, a natural warming of sea water in the tropical Pacific Ocean.

The warmth last year factored into extreme weather around the globe that brought widespread death and destruction from hurricanes, wildfires, floods and heat waves.

“Temperatures over the planet as a whole continue the rapid warming trend we’ve seen over the last 40 years,” said NASA scientist Gavin Schmidt.

The most recent cooler-than-average year was 1976. Since then, the globe has experienced a stretch of 41 consecutive warmer-than-average years.

The planet’s average surface temperature has risen about 2 degrees Fahrenheit during the past century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere, NASA said.

“This is human-caused climate change in action,” said Nobel Prize winning chemist Mario Molina of the University of California San Diego, who wasn’t part of any of the measuring teams. “Climate is not weather, (which) can go up and down from year to year. What counts is the longer-term change, which is clearly upwards.”

Both analyses show the five warmest years on record all have taken place since 2010 with the past four years rising to the four warmest since 1880, when record-keeping began.

The two federal agencies maintain separate global temperature data sets. The minor difference in rankings is due to the different methods used to analyze global temperatures, although over the long-term the agencies' records remain in strong agreement.

NOAA's analysis does not include data from the Arctic, while NASA's does, NOAA climate scientist Deke Arndt said. The Arctic has been warming faster than any part of the world.

The average temperature across global land and ocean surfaces reached 58.51 degrees last year, 1.51 degrees above the 20th-century average, according to NOAA. Meanwhile, NASA measured the global temperature as 1.62 degrees above the 1951-1980 average.

December was warmer-than-average as well, marking the planet's 396th consecutive warmer-than-average month.

“This announcement should shock no one," said Lou Leonard of the World Wildlife Fund. "The key question is what we do about it. With the costs of inaction piling up, Washington, D.C., is largely looking the other way. So it is up to a new class of leaders from American businesses, universities, cities and states to pick up the slack."